Apex domains cannot have CNAME records.
Question and response
Question
dig ssl-secured.eu. NS
Answer
ssl-secured.eu. 4 NS ns3.domaintechnik.at.
ssl-secured.eu. 4 NS ns1.domaintechnik.at.
ssl-secured.eu. 4 NS ns2.domaintechnik.at.
ssl-secured.eu. 4 NS ns4.domaintechnik.at.
Authority
The response has no authority records.
Additional
ns1.domaintechnik.at. 4 A 213.145.228.70
ns2.domaintechnik.at. 4 A 213.145.228.140
ns3.domaintechnik.at. 4 A 213.145.232.70
ns4.domaintechnik.at. 4 A 83.151.27.254
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0